Selective Syntheses of Vicinal Dimethyl Chirons by Hydrogenation

Significance

Acyclic fragments containing syn- and anti-1,2-dimethyl substitution patterns are found in various natural products. Several methods to construct these units exist including, among others, Grignard addition to γ-chiral centers, desymmetrization of meso-1,2-dimethyl substrates, and conjugate addition followed by enolate trapping. In the present report, silyl ether or free hydroxyl-trisubstituted alkene substrates ­derived from the Roche ester are hydrogenated with 1 to provide the corresponding anti- and syn-1,2-dimethyl chirons in high selectivities.